1. Field of the Invention
The present invention relates to a power transmission chain pin and a manufacture method thereof, and more specifically, to a power transmission chain pin suitable for a continuously variable transmission (CVT) of a vehicle such as an automobile and a manufacture method thereof.
2. Related Art
As shown in FIG. 9, as a continuously variable transmission for an automobile, there is a known chain type continuously variable transmission including a drive pulley (2) which has a stationary sheave (2a) and a movable sheave (2b) and which is disposed in an engine; a driven pulley (3) which has a stationary sheave (3b) and a movable sheave (3a) and which is disposed in a drive wheel; and a power transmission chain (1) with an endless shape which is wound around the pulleys. At this time, a hydraulic actuator allows the movable sheaves (2b) and (3a) to move close or away to or from the stationary sheaves (2a) and (3b) so as to clamp the chain (1) by hydraulic pressure. By means of the clamp force, a contact load occurs between the pulleys (2) and (3) and the chain (1) so as to transmit a torque by a friction force of the contact portion.
Also, JP-A-2004-251385 discloses a power transmission chain including a plurality of links having front and back insertion through holes through which pins are inserted; and a plurality of first and second pins which connect links, which are arranged in the chain width direction so as to allow the front insertion through hole of one link to correspond to the back insertion through hole of the other link, so as to be bendable in the longitudinal direction. In JP-A-2004-251385, the pin is manufactured such that a predetermined bar-like intermediate material is formed by a forging work, a turning work, a cutting work, and then a grinding work is performed on the bar-like intermediate material so as to allow a pin section to have a predetermined shape.
In the power transmission chain in JP-A-2004-251385, a plurality of pins are used, but it takes much time for working a pin, since an end portion of the pin needs to be subjected to a grinding work, which induces an increase in manufacture cost.